The known physiological actions of gastrin on the oxyntic gland mucosa are the stimulation of growth and acid secretion. This laboratory has identified and characterized a gastrin receptor present in rat oxyntic gland mucosal membranes. It is likely that this receptor is responsible for the trophic effect of gastrin. However, the correlation of receptor binding with this biological response is difficult to verify due to a mixed cell population in any preparation. Cell culture provides a valuable tool so that the trophic effects of gastrin can be examined directly and other parameters such as gastrin binding and calcium uptake can be evaluated. The objectives of this study are three-fold. First, to examine gastrin binding to the cultured gastric mucosal cells. Second, to determine if there is a gastrin-dependent calcium uptake and whether this uptake can be correlated with binding. Third, to demonstrate the gastrin-dependent trophic effect and to correlate this effect with binding. A cell line will be established and characterized in the standard way. The trophic effect of gastrin will be monitored through DNA & protein measurements and by cell counts of cultured cells and by evaluating tumor formation in rats. These studies will have significance in understanding the regulation of mucosal turnover in normal tissue which can then serve as a basis for studying abnormal conditions such as pernicious anemia and gastritis.